Steel: 31CrV3 47-52 HRC Chromizing H: 60 mm Length: 185 mm An angle hex key (also known as an "Allen key") is used for working with fasteners that have an internal hexagonal shape. Angle keys combine two levers in their construction: an extended lever for applying maximum force and a short lever for quick rotation. They are also used for working with fasteners in confined spaces. The high strength characteristics allow avoiding damage to the edges of the fasteners. You can also purchase a set of hex keys.